Methanol Oxidation Catalytic Performance Enhancement via Constructing Pd-MgAl.sub.2O.sub.4 Interface and its Reaction Mechanism Investigation

The methanol oxidation reaction is a promising route to eliminating trace amount of methanol in exhaust gases which aroused serious environmental concern. In this work, a novel Pd/MgAl.sub.2O.sub.4 catalyst was prepared to construct the metal-support interface and employed in the methanol oxidation reaction. The reaction results show that the Pd/MgAl.sub.2O.sub.4 catalyst could achieve 100% methanol oxidation at 198 â over the Pd/MgO and Pd/Al.sub.2O.sub.3 catalysts. The high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), CO-chemisorption, H.sub.2 temperature programmed reduction (H.sub.2-TPR), and CO diffuse reflectance infrared Fourier transformed spectroscopy (CO-DRIFTS) show that the Pd was uniformly distributed over the MgAl.sub.2O.sub.4 support due to strong interaction between Pd and MgAl.sub.2O.sub.4. The mechanism studies show that the abundant Pd-MgAl.sub.2O.sub.4 interfaces significantly contributed to the reaction enhancement. The Pd-MgAl.sub.2O.sub.4 interfaces could greatly enhance the oxidation reaction at a lower temperature with the assistance of oxygen vacancies compared with traditional oxide catalysts, which was confirmed by methanol temperature program surface reaction (MeOH-TPSR) experiments. In-situ DRIFTS is carried out to elucidate the reaction mechanism and establish the structure - activity relationship: the methanol could be effectively absorbed on the MgAl.sub.2O.sub.4 support with oxygen vacancies to form bidentate formate, then the Pd species assisted the intermediates converting to CO.sub.2 product. The Pd/MgAl.sub.2O.sub.4 catalyst and its enhancement mechanism investigation provided a potential strategy in the VOCs removal catalysis development.